In the version you are using, it is still required; that's the docs leading the released code by a step (sorry). The version you are using also doesn't enforce limits well, so it allows values that could produce no result, or store more data than needed.
For example, given your retention of 60 and interval of 5, there would be r/i+1 = 13 samples in the series. But if you specify depth of 2, then only the most recent 2d-1 = 3 samples are considered... the other 10 samples don't contribute to the result value. A depth of 7 would be the best match for the given interval and retention (just mathematically, ignoring your semantic goals).


